1. Field of the Invention
The present invention relates to a plasma treatment method by which substrates such as semiconductor wafers are etched or sputtered under plasma atmosphere. It also relates to a plasma treatment apparatus for the same.
2. Description of the Related Art
Recently, semiconductor devices are more and more highly integrated and the plasma treatment is therefore asked to have a finer workability in their making course. In order to achieve such a finer workability, the process chamber must be decompressed to a greater extent, plasma density must be kept higher and the treatment must have a higher selectivity. In the case of the conventional plasma treatment methods, however, high frequency voltage becomes higher as output is made larger, and ion energy, therefore, becomes stronger than needed. The semiconductor wafer becomes susceptible to damage, accordingly. Further, the process chamber is kept about 250 mTorr in the case of the conventional methods and when the degree of vacuum in the process chamber is made higher (or the internal pressure in the chamber is made smaller), plasma cannot be kept stable and its density cannot be made high.